Wiring harnesses are used extensively in both commercial and military aviation and space applications to interconnect physically separate subassemblies of an electronics system. A wiring harness typically comprises a bundle of insulated wires or cables of various well-known types, each of which terminates at its opposite ends in a respective contact of an electrical connector of various known types, and may include one or more “branches” that extend from a main bundle and terminate in an electrical connector. One such harness connector that is used widely in both airborne and space applications is the military standard Mil-DTL-24308 connector, more widely referred to as a “D-subminiature,” or simply, “D-sub” connector.
D-sub connectors are provided in complementary, mating, i.e., male-female, pairs of connectors, each comprising a plurality, typically between 9 and 78, of either pins or sockets, typically of copper alloy, that are encased in a dielectric insert, typically plastic, that is surrounded by a shell, typically metal, that is “D” shaped for “polarization” purposes, i.e., such that the connector pair can mate with each other in only one, correct, engagement. The shell includes a pair of mounting flanges disposed on opposite sides of the insert, and each flange is typically provided with an aperture containing one of a pair of complementary, captivated fasteners, e.g., a threaded nut-and-screw pair, that can be used both to mount the respective connector halves to, e.g., a mounting surface, and also to pull the two halves into operative engagement with each other.
In one typical application of D-sub connectors, a half of a mating pair of the connectors is mounted in an opening in a front or rear panel of an electronics unit, and wires or cables conveying electrical signals to or from the interior of the unit are respectively coupled to the back ends of the contacts, i.e., the pins or sockets, thereof. A wiring harness containing a bundle of wires and cables, each respectively coupled to the back ends of the contacts of the other half of the mating connector pair, is arranged to convey the respective signals of the unit to or from the other units of the system. The wiring harness thus defines a simple, convenient and reliable signal interface that enables each of the subassembly units of the system to be easily and quickly electronically coupled to or decoupled from the system and, e.g., replaced with another unit for maintenance and repair purposes.
Although wiring harnesses can provide convenient, reliable electrical interfaces between the units of an electronics system, they are subject to certain recognized problems that are inherent thereto. One of these relates to the strain that can be imposed on the connection between the contacts of the connectors and the wires or cables of the harness due to forces being applied to one of the connector or the wire bundle independently of the other. This can result, for example, from shock and/or vibration forces acting on the harness during flight, or as a result of maintenance personnel tugging on the harness to reroute it, or to disengage a connector of the harness from engagement with a mating panel connector. In such instances, it is possible in some cases for the resulting strain between the connector and the harness to break some of the wires of the harness, or to disconnect them from their respective connector contact.
In light of this problem, it is known to provide a stress relief mechanism on a harness connector that enables the connector and the harness to be coupled together mechanically at the rear of the connector, such that forces applied to either of the two is transmitted directly to the other through the strain relief mechanism, rather than through the connections of the wires to the respective connector contacts. However, connectors provided with such strain relief mechanisms are typically heavier and more expensive than those without them, and are often not utilized where weight is of a concern. Additionally, such connectors must be installed on the harness at the time the harness is initially fabricated, so that a later decision to retrofit a wiring harness with such connectors necessitates a complete disassembly of all of the wires of the harness from the contacts of the existing connectors, and a reassembly of the wires with the contacts of the new connectors, a costly and time-consuming procedure.
Accordingly, there is a long felt but as yet unsatisfied need in this field for an inexpensive, reliable and light weight strain relief mechanism for a wiring harness connector that can be installed on or removed from the connector and harness either at the time the harness is fabricated, or later, e.g., after the harness has been deployed in the field, quickly and simply, and without the need to remove all of the wires or contacts from the connector.